Bathtub lift for seniors and the handicapped

ABSTRACT

In a bathtub lift for seniors and the handicapped comprising a scissor-type lifting mechanism whereby a seat plate is vertically adjustable relative to a floor stand, a back rest connected to the seat plate, a telescopic lifting device that is connected to the back rest as well as to the seat plate on one hand and supported on the floor stand on the other hand, and a drive unit to drive the lifting device, provision is made for the lifting device to comprise a driven gearwheel, which, together with a driving gearwheel that is connected to the drive unit forms a gear mechanism and is engageable with this driving gearwheel, wherein the two gearwheels are separable from one another by a pulling force acting upon the lifting device resulting from a body part of a bathing person getting trapped.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the invention

[0002] The present invention is concerned with a bathtub lift for seniors and the handicapped, comprising a scissor-type lifting mechanism whereby a seat plate is vertically adjustable relative to a floor stand, a back rest that is connected to the seat plate, a telescopic lifting device that is connected to the back rest as well as to the seat plate on one hand and supported on the floor stand on the other hand, and a drive unit to drive the lifting device.

[0003] 2. Background Art

[0004] Bathtub lifts of this type are generally controlled by means of a hand control element, which comprises a button to move the seat plate up and down. These bathtub lifts furthermore also have an emergency off switch, which immediately interrupts any movement of the seat plate.

[0005] It is a shortcoming of these known solutions, however, that the seat plate does not automatically interrupt its downward movement when a body part of a bathing person gets trapped.

[0006] From other applications, such as e.g., adjustable patient beds or height-adjustable tables, safety devices that respond automatically are known in lifting devices. In one safety device, provision is made for the inner tube of a spindle drive to be connected to the spindle nut not solidly but merely form-fitting, so that a turning moment and pressure forces can be transferred, but no pulling forces. This can be implemented, for example, by means of a splined shaft.

[0007] A shortcoming of this described spindle drive is its particularly large size because of this safety device.

[0008] In another safety device, provision is made for transferring a turning moment via a wrap spring that sits between two cylinders, which are not connected to one another. In one direction of rotation of the drive shaft, this spring closes and transfers the turning moment, whereas in the opposite direction of rotation it opens and thus does not transfer any turning moment. This design also requires a very considerable amount of space.

[0009] An auto-stop via an integrated microswitch, which is actuated by a force that results when a body part of a person gets trapped, and which interrupts the power supply to the drive motor, is also used in these applications.

[0010] It is also known in these designs to switch off the motor by means of an electronic device when the motor current increases.

SUMMARY OF THE INVENTION

[0011] It is an object of the present invention to improve a known bathtub lift in such a way that the downward movement of the seat plate is stopped reliably, quickly and automatically by means of a pulling force resulting from a body part of a bathing person getting trapped, which acts upon the lifting device. Provision is furthermore made for the bathtub lift of the above type to be designed such that expensive electric circuits may be dispensed with and the space requirement is particularly small.

[0012] This object is met according to the invention in such a way that the lifting device comprises a driven gearwheel which, together with a driving gearwheel that is connected to the drive unit, forms a gear mechanism and is engageable with this driving gearwheel, and the two gearwheels are separable from one another by a pulling force resulting from a body part of a bathing person getting trapped and acting upon the lifting device.

[0013] This design permits the implementation of a particularly space-saving and reliable anti-trapping safety device, which does not incorporate any sensitive electronic components.

[0014] The invention furthermore advantageously provides for the gear mechanism to be designed as a toothed gearing and specifically as a bevel gear pair, wherein the driven gearwheel is engageable with the driving gearwheel by means of a pressure spring.

[0015] The gearwheels transfer the motions of revolution in a form-fitting manner from a drive shaft of the drive unit to a driven shaft of the lifting device that effects a vertical adjustment of the seat plate. The desired number of revolutions or the required turning moment at the driven shaft is selectable via the number of teeth of the gearwheels and thus via the ratio of transmission.

[0016] The gearwheels are separable from one another when the pulling force resulting from a body part of a bathing person getting trapped is greater than the counteracting pressure force from the pressure spring. Controls or other electric circuits thus are not required as this anti-trapping safety device comprises only mechanically acting components.

[0017] The lifting device is preferably designed as a threaded spindle drive and comprises an outer spindle tube inside which a lifting spindle with a spindle nut is provided and an inner spindle tube is connected to the spindle nut by means of a spindle foot.

[0018] Since the seat plate is moved in a straight line, the use of a threaded spindle drive is particularly advantageous. The inside spindle tube that is connected to the spindle nut is supported in a spindle foot receptacle of the floor support. A revolution of the spindle effects an axial movement of the spindle nut and thus a height adjustment of the seat plate.

[0019] Since the pressure spring is supported on a sleeve that is fixed immovably inside the outer spindle tube, the driven gearwheel normally engages with the driving gearwheel. The end of the pressure spring that faces the spindle nut is fixed in its position by this sleeve.

[0020] It is advantageous that the spindle foot is secured in the spindle foot receptacle of the floor stand in a manner so that it is axially moveable, and a contact plate with a recess for the spindle foot covers the spindle foot receptacle. The spindle foot encompasses an annular shoulder, which, when an axial movement results from a body part of a bathing person getting trapped, rests against the contact plate.

[0021] When the annular shoulder rests against the contact plate, the inner tube transfers a pulling force onto the spindle, which causes the gearwheels to be separated from one another. This design results in a cost-effective and reliable implementation of an anti-trapping safety device.

[0022] The invention will be explained in more detail below based on a preferred embodiment in conjunction with the drawing, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

[0023]FIG. 1 shows a schematic side view of an inventive bathtub lift,

[0024]FIG. 2 shows a longitudinal section through the lifting device and through the driving gearwheel that is connected to a drive shaft, and

[0025]FIG. 3 shows a section through a spindle foot receptacle incorporating the spindle foot.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0026] Depicted in FIG. 1 is a bathtub lift in its entirety. It comprises a floor stand 1 with feet 51 that is placed onto the floor of a bathtub, which is not shown. The bathtub lift furthermore comprises a seat plate 2, which is vertically adjustable relative to the floor stand 1 by means of a scissor-type lifting mechanism 3. A pivot-mounted back rest 4 is hinged at the seat plate 2 by means of a pivot joint 5. To raise or lower the seat plate 2, a lifting device 52 is used that is driven via a drive unit 6 and is supported with its upper end 8 in a support device 9 at the rear of the back rest 4 and supported with its lower end 10 in the floor support 1.

[0027] The scissor-type lifting mechanism 3 that is disposed between the floor stand 1 and the seat plate 2 comprises one each scissor-type articulated cross-brace on each side of the floor stand I and the seat plate 2. Alternately, a design with two pivot arms would be possible as well. Each scissor-type articulated cross-brace is formed by two braces 12, 13 that are connected to one another in the crosswise center by means of a pivot joint 11, and the upper free end 14 of the brace 12 is supported on a pivot bearing 15 of the seat plate 2 and the lower end 16 of the brace 13 is supported on a pivot bearing 17 of the floor stand 1. The free end 18 of the brace 13 and the free end 19 of the brace 12 are slide-mounted via sliding blocks inside the guide rails 20 of the seat plate 2, or 21 of the floor stand 1.

[0028] The lifting device 52 comprises a lifting spindle 7, which has a longitudinal axis 22 and a trapezoidal joint 23. The lifting spindle 7 carries a spindle nut 24 with a trapezoidal internal thread, which extends into an inside spindle tube 25 and is immovably connected to the same. The inside spindle tube 25 encompasses the lifting spindle 7 and a fastening section 26 of the spindle nut 24 that extends into the inside spindle tube 25. The inside spindle tube 25 forms the lower end 10 of the lifting device 52 and incorporates a spindle foot 27 that is supported in a spindle foot receptacle 28 of the floor stand 1.

[0029] The lifting device 52 furthermore incorporates an outer spindle tube 29, which encompasses both the spindle nut 24 as well as the inner spindle tube 25 in such a way that the spindle nut 24 rests, with an annular section 30, against the inside of the outer spindle tube 29 to effect a rotatory relative movement between the lifting spindle 7 and the spindle nut 24.

[0030] At the end opposite the spindle foot 27, the lifting spindle 7 has a peg 31 that is tapered in cross section. A driven gearwheel 32, which is in engagement with a driving gearwheel 33 of the drive unit 6, is connected to the spindle peg 31 integral in rotation therewith. The driving gearwheel 33 is supported, integral in rotation with it, by a drive shaft 34 of the drive unit 6, in such a way that the drive shaft 34 has a longitudinal axis 35, which extends perpendicular to the longitudinal axis 22 of the lifting spindle 7. The driving gearwheel 33 and the driven gearwheel 32 together form a bevel gear pair 50. The diameters of the gearwheels 32, 33 are identical.

[0031] Inserted into the outer spindle tube 29 on the side facing the driven gearwheel 32 is a receiving sleeve 36 that is fixed in its position by an annular projection 37 that rests against the face end of the outer spindle tube 29. The end of the receiving sleeve 36 opposite the annular projection 37 is equipped with an annular bottom section 38, which secures a helical pressure spring 39 in an axial position. The other end of the pressure spring 39 is held in a receiving slot 40 of a further receiving sleeve 41 that is mounted adjacent to a rolling bearing 42 that rests against the driven gearwheel 32. The two receiving sleeves 36, 41 are disposed at a distance from one another. The rolling bearing 42 is fixed in its position by the driven gearwheel 32 and a securing disk 43, which is pushed over the spindle peg 31 in such a way that the securing disk 43 rests against the transition point from the spindle peg 31 to the lifting spindle 7.

[0032] The force that is generated by the lifting device 52 is applied by a locking ring 44 onto the seat plate 2 that is to be adjusted, said locking ring 44 being connected to the outer spindle tube 29 in a form-fitting manner. At the seat plate 2, the locking ring 44 is supported in pendulum fashion.

[0033] As can be seen particularly from FIG. 3, the spindle foot 27 has a conical cross section. The spindle foot 27 is supported with its tip at a base 45 of the spindle foot receptacle 28, which is formed in the floor stand 1. The spindle foot receptacle 28 comprises a contact plate 46 with a recess 47 for the spindle foot 27. The contact plate 46 is disposed at a distance from the base 45 and covers the spindle foot receptacle 28. The spindle foot 27 has an annular shoulder 48, the diameter of which is larger than the diameter of the recess 47.

[0034] The operation of the bathtub lift will be described below. The drive shaft 34 is driven by the preferably battery-operated drive unit 6. The driving gearwheel 33 that is connected to the drive shaft 34 is thus driven as well and transfers the turning moment that is produced by the drive unit 6 onto the driven gearwheel 32, which is disposed on the spindle peg 31 integral in rotation therewith, which puts the lifting spindle 7 into rotation. The spindle peg 31 and the lifting spindle 7 may be regarded as a driven shaft. The rotation of the lifting spindle 7 effects an axial movement of the spindle nut 24. The movement of the spindle nut 24 causes the inner spindle tube 25 that is connected to the spindle nut 24 to move as well, with the result that the seat plate 2, which is connected to the outer spindle tube 29 via the locking ring 44 is adjusted in its height. The driven gearwheel 32 is in engagement with the driving gearwheel 33 due to the spring force of the pressure spring 39. A safety nut 49 that is disposed in a section adjacent to the spindle peg 31, is provided on the lifting spindle. It serves as a safety element in case the spindle nut 24 should break.

[0035] If a body part of a bathing person or other object is located between the seat plate 2 and floor stand 1 when the seat plate 2 is being lowered, the adjustment of the seat plate 2 is blocked and an upward pulling force that results from the trapped body part acts upon the inner spindle tube 25 since the spindle nut 24 moves upward when the seat plate 2 is being lowered. This pulling force causes the spindle foot 27 to move away from the floor stand 1 until the annular shoulder 48 of the spindle foot 27 rests against the contact plate 46. This causes the pulling force resulting from the trapped body part to be transferred via the inner spindle tube 25 and via the spindle nut 24 that is connected to the inner spindle tube 25, onto the lifting spindle 7. Due to this resulting downward force the lifting spindle 7 is pulled along with the driven gearwheel 32 that is disposed on the spindle peg 31 in the direction of the floor stand 1. As this force increases, the driven gearwheel 32 is pulled down until it no longer engages with the driving gearwheel 33. As a result, the seat plate 2 automatically comes to a standstill without the need to actuate an emergency off switch or other switch. When the body part that has become trapped between the floor stand 1 and the seat plate 2 is freed, the pressure spring 39 moves the driven gearwheel 32 back into engagement with the driving gearwheel 33. The turning moment that is produced by the drive unit 6 is then again transferred via the gearwheels 33, 32 onto the lifting spindle 7 and the movement of the seat plate 2 continues. 

What is claimed is:
 1. A bathtub lift for seniors and the handicapped, comprising a scissor-type lifting mechanism (3) whereby a seat plate (2) is vertically adjustable relative to a floor stand (1), a back rest (4) connected to the seat plate (2), a telescopic lifting device (52), that is connected to the back rest (4) as well as to the seat plate (2) on one hand, and supported on the floor stand (1) on the other hand, also a drive unit (6) to drive the lifting device (52), wherein the lifting device (52) comprises a driven gearwheel (32), which together with a driving gearwheel (33) that is connected to the drive unit (6) forms a gear mechanism (50) and is engageable, wherein the two gearwheels (32, 33) are separable by a pulling force acting upon the lifting device (52) that results from the body part of a bathing person getting trapped.
 2. A bathtub lift according to claim 1, wherein the gear mechanism (50) is designed as a toothed wheel gear.
 3. A bathtub lift according to claim 1, wherein the gear mechanism (50) is designed as a bevel gear pair.
 4. A bathtub lift according to claim 1, wherein the driven gearwheel (32) is engageable with the driving gearwheel (33) by means of a pressure spring (39).
 5. A bathtub lift according to claim 1, wherein the lifting device (52) is designed as a threaded spindle drive comprising an outer spindle tube (29) wherein a lifting spindle (7) with a spindle nut (24) is provided, wherein an inner spindle tube (25) with a spindle foot (27) is connected to the spindle nut (24).
 6. A bathtub lift according to claim 4, wherein the pressure spring (39) is supported on a receiving sleeve (36) that is fixed immovably inside the outer spindle tube (29).
 7. A bathtub lift according to claim 5, wherein the spindle foot (27) is secured axially movable in a spindle foot receptacle (28) of the floor stand (1).
 8. A bathtub lift according to claim 1, characterized in that a contact plate (46) with a recess (47) for the spindle foot (27) covers the spindle foot receptacle (28).
 9. A bathtub lift according to claim 1, wherein the spindle foot (27) is provided with an annular shoulder (48), which, during an axial movement resulting from a body part of a bathing person getting trapped, rests against the contact plate (46). 